Law enforcement personnel, firemen, rescue personnel, and others frequently must force open locked doors in order to gain entrance to premises so that they can perform their duties therein. There are a number of different procedures for breaking through such locked doors, ranging from firing bullets into the locks; to axes for breaking the doors down; to lock picks for picking the locks; to crow bars; and so on. There are various drawbacks to such procedures, as for example, fired bullets can strike people inside or outside of the premises; an axe is difficult to use, time consuming, and can cause personal injury; crowbars are time consuming and sometimes ineffective; and lock picking requires special training, skills and knowledge.
It would be very desirable from a safety standpoint, and from an efficiency standpoint, to have a specialized tool which could be used to quickly neutralize a variety of door locks, wherein the force used to neutralize the locks is a captive force; and wherein no special skill is required to use the tool. A specialized powder-actuated tool would be very amenable to the aforesaid use.
Powder actuated tools are well known in the construction field for driving fasteners, such as nails, studs, or anchors, into a relatively hard supporting surface, such as concrete. Such tools utilize a piston for driving the fastener. The piston is typically driven by an explosive blank cartridge. Combustion gases generated from the cartridge drive the piston from a breechward position to a muzzleward position to drive the fastener into the supporting surface.
The explosive charge will occasionally overdrive the fastener driving piston, a condition which occurs when the piston is driven past the piston return pawl and into the buffer. This always occurs when the operator forgets to insert a fastener into the muzzle of the tool, and can also occur occasionally at other times. Such an occurrance is undesirable in a fastener driving tool.